The present invention relates to a support arm which automatically swings into position to support the cords and tilt rod in the head rail of a vertical blind as the carrier assembly traverses to open the blind (retracts). As the carrier assembly traverses to close the blind (extends), the support arm automatically swings out of the way so as not to interfere with the motion of the carrier assembly.
Typically, a vertical blind transport system will have a top head rail, which both supports the blind and hides the mechanisms that are used to traverse the vanes and the mechanisms that are used to tilt the vanes. The carrier assembly is fully supported along its entire sliding length, as each carrier must be able to support the weight of its corresponding vane. Thus, when the carrier assembly extends, it assists in supporting both the tilt rod and the traverse cords. However, as the vanes traverse open, the tilt rod and the traverse cords remain behind and are thus unsupported except at one end by the head rail and at the other end by the lead carrier which is retreating, leaving an ever-widening unsupported span. The traverse cords, and even the tilt rod, tend to drape down through this unsupported span and stick out past the open bottom of the head rail. This is unsightly and may cause operational problems.
The prior art has support arms which, when properly installed, swing across the head rail as the lead carrier retreats, so as to provide a support for the sagging traverse cords and tilt rod. These support arms swing away, back to a stowed position, when the lead carrier is traversing closed and can thus take over the support function otherwise afforded by the support arm.
However, if the prior art support arm is in an incorrect position as the carrier assembly is traversing, the support arm will be rendered ineffective. In one instance, if the support arm is in the stowed position as the carrier assembly traverses to the closed position (extends), the lead carrier will impact upon and will not move past the support arm, causing the carrier train to lock up. If the operator uses extreme force to overcome the lock-up, the carrier train will push the support arm to the end of the head rail leaving the support arm inoperative. In the second instance where the support arm is in the xe2x80x9cspanning positionxe2x80x9d(not stowed position) as the carrier assembly traverses to the open position (retracts), the first carrier to come across the support arm will simply drag the support arm with it. The holding force of the support arm is not enough to cause the operator to stop traversing the blind. The support arm is forcibly moved along with the carrier train into an ineffective position, where it remains.
The present invention provides a support arm design which has the advantages of prior art support arms, plus it eliminates the problems with prior art support arms which may become inoperative or ineffective if improperly installed or if they are accidentally moved to an improper position during normal operation.
In the current invention, as the carrier assembly retracts, the lead carrier activates the support arm, swinging it into the spanning position so as to support the traverse cords and the tilt rod. As the carrier assembly extends, the lead carrier stows the support arm so that it does not interfere with the carrier train. Should the support arm be in the incorrect position, so that it is stowed when it should be spanning, the design of the present invention allows for the support arm and the carrier assembly to xe2x80x9cbypassxe2x80x9d each other, and yet be ready to properly cooperate with each other to engage the support arm in the right place and at the right time the next time the carrier assembly traverses the blind.
The support arm assembly has a ramp, and, in the event that the support arm is already in the stowed position when the carrier assembly is extending (when the support arm should have been in the spanning position instead of the stowed position), the lead carrier guide activating post will move up and over the support arm ramp to bypass the support arm, but will activate the arm when it passes back (retracts) during the next cycle. In the event that the support arm is already in the spanning position when the carrier assembly is retracting (when the support arm should have been in the stowed position instead of the spanning position), the support arm will bring the carrier train to a complete stop. The holding force of the support arm is strong enough to stop the carrier train and to cause the operator to traverse the blind back to the closed position, which will cause the next carrier to reset the support arm to the correct, stowed position.